Effect of Heat Treatment of Milk on the Sensory and Rheological Quality of Dahi Prepared from Cow Milk
Dahi is a popular fermented Indian dairy product prepared by fermenting the milk by lactic acid bacteria. The texture of dahi depends mainly on the heat treatment given to milk. Cow milk (3.5% fat and 8.5% SNF) was subjected to two separate treatments: (1) heating at 63oC for 30 min and (2) boiling treatment without holding period. The milk was cooled to about 40oC and inoculated with Lactococcus lactis culture and incubated at 30oC for about 12 hours. The dahi formed was chilled to 5oC and evaluated for quality. Firmness, consistency and index of viscosity as measured by Texture Analyser increased with increased heat treatment and the highest values were observed in dahi prepared from boiled milk. Boiling treatment of milk resulted in least syneresis of whey in the curd. Based on the results, it was recommended that milk be subjected to boiling treatment to produce best quality dahi.